RESUMO
We analysed DNA methylation data from 30 datasets comprising 3474 individuals, 19 tissues and 8 ethnicities at CpGs covered by the Illumina450K array. We identified 4143 hypervariable CpGs ('hvCpGs') with methylation in the top 5% most variable sites across multiple tissues and ethnicities. hvCpG methylation was influenced but not determined by genetic variation, and was not linked to probe reliability, epigenetic drift, age, sex or cell heterogeneity effects. hvCpG methylation tended to covary across tissues derived from different germ-layers and hvCpGs were enriched for proximity to ERV1 and ERVK retrovirus elements. hvCpGs were also enriched for loci previously associated with periconceptional environment, parent-of-origin-specific methylation, and distinctive methylation signatures in monozygotic twins. Together, these properties position hvCpGs as strong candidates for studying how stochastic and/or environmentally influenced DNA methylation states which are established in the early embryo and maintained stably thereafter can influence life-long health and disease.
Assuntos
Metilação de DNA , Embrião de Mamíferos , Humanos , Metilação de DNA/genética , Reprodutibilidade dos Testes , Embrião de Mamíferos/metabolismo , Ilhas de CpG , EtnicidadeRESUMO
Recurrent pregnancy loss (RPL) is defined as two or more consecutive miscarriages and affects an estimated 1.5% of couples trying to conceive. RPL has been attributed to genetic, endocrine, immune and thrombophilic disorders, but many cases remain unexplained. We investigated a Bangladeshi family where the proband experienced 29 consecutive pregnancy losses with no successful pregnancies from three different marriages. Whole exome sequencing identified rare genetic variants in several candidate genes. These were further investigated in Asian and white European RPL cohorts, and in Bangladeshi controls. FKBP4, encoding the immunophilin FK506-binding protein 4, was identified as a plausible candidate, with three further novel variants identified in Asian patients. None were found in European patients or controls. In silico structural studies predicted damaging effects of the variants in the structure-function properties of the FKBP52 protein. These were located within domains reported to be involved in Hsp90 binding and peptidyl-prolyl cis-trans isomerase (PPIase) activity. Profound effects on PPIase activity were demonstrated in transiently transfected HEK293 cells comparing wild-type and mutant FKBP4 constructs. Mice lacking FKBP4 have been previously reported as infertile through implantation failure. This study therefore strongly implicates FKBP4 as associated with fetal losses in humans, particularly in the Asian population.
Assuntos
Aborto Habitual/genética , Sequenciamento do Exoma/métodos , Proteínas de Ligação a Tacrolimo/genética , Exoma/genética , Feminino , Predisposição Genética para Doença , Células HEK293 , Humanos , Mutação de Sentido Incorreto/genética , Linhagem , Gravidez , Estrutura Secundária de ProteínaRESUMO
PURPOSE: Much of the heredity of melanoma remains unexplained. We sought predisposing germline copy-number variants using a rare disease approach. METHODS: Whole-genome copy-number findings in patients with melanoma predisposition syndrome congenital melanocytic nevus were extrapolated to a sporadic melanoma cohort. Functional effects of duplications in PPP2R3B were investigated using immunohistochemistry, transcriptomics, and stable inducible cellular models, themselves characterized using RNAseq, quantitative real-time polymerase chain reaction (qRT-PCR), reverse phase protein arrays, immunoblotting, RNA interference, immunocytochemistry, proliferation, and migration assays. RESULTS: We identify here a previously unreported genetic susceptibility to melanoma and melanocytic nevi, familial duplications of gene PPP2R3B. This encodes PR70, a regulatory unit of critical phosphatase PP2A. Duplications increase expression of PR70 in human nevus, and increased expression in melanoma tissue correlates with survival via a nonimmunological mechanism. PPP2R3B overexpression induces pigment cell switching toward proliferation and away from migration. Importantly, this is independent of the known microphthalmia-associated transcription factor (MITF)-controlled switch, instead driven by C21orf91. Finally, C21orf91 is demonstrated to be downstream of MITF as well as PR70. CONCLUSION: This work confirms the power of a rare disease approach, identifying a previously unreported copy-number change predisposing to melanocytic neoplasia, and discovers C21orf91 as a potentially targetable hub in the control of phenotype switching.
Assuntos
Melanoma , Nevo , Neoplasias Cutâneas , Humanos , Imuno-Histoquímica , Melanoma/genética , Fenótipo , Neoplasias Cutâneas/genéticaRESUMO
BACKGROUND: Silver-Russell syndrome is an imprinting disorder that restricts growth, resulting in short adult stature that may be ameliorated by treatment. Approximately 50% of patients have loss of methylation of the imprinting control region (H19/IGF2:IG-DMR) on 11p15.5 and 5%-10% have maternal uniparental disomy of chromosome 7. Most published research focuses on the childhood phenotype. Our aim was to describe the phenotypic characteristics of older patients with SRS. METHODS: A retrospective cohort of 33 individuals with a confirmed molecular diagnosis of SRS aged 13 years or above were carefully phenotyped. RESULTS: The median age of the cohort was 29.6 years; 60.6% had a height SD score (SDS) ≤-2 SDS despite 70% having received growth hormone treatment. Relative macrocephaly, feeding difficulties and a facial appearance typical of children with SRS were no longer discriminatory diagnostic features. In those aged ≥18 years, impaired glucose tolerance in 25%, hypertension in 33% and hypercholesterolaemia in 52% were noted. While 9/33 accessed special education support, university degrees were completed in 40.0% (>21 years). There was no significant correlation between quality of life and height SDS. 9/25 were parents and none of the 17 offsprings had SRS. CONCLUSION: Historical treatment regimens for SRS were not sufficient for normal adult growth and further research to optimise treatment is justified. Clinical childhood diagnostic scoring systems are not applicable to patients presenting in adulthood and SRS diagnosis requires molecular confirmation. Metabolic ill-health warrants further investigation but SRS is compatible with a normal quality of life including normal fertility in many cases.
Assuntos
Fator de Crescimento Insulin-Like II/genética , RNA Longo não Codificante/genética , Síndrome de Silver-Russell/genética , Dissomia Uniparental/genética , Adolescente , Adulto , Idoso , Metilação de DNA/genética , Epigênese Genética , Feminino , Impressão Genômica/genética , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Qualidade de Vida , Síndrome de Silver-Russell/patologia , Dissomia Uniparental/patologia , Adulto JovemRESUMO
Mutations in SNX14 cause the autosomal recessive cerebellar ataxia 20 (SCAR20). Mutations generally result in loss of protein although several coding region deletions have also been reported. Patient-derived fibroblasts show disrupted autophagy, but the precise function of SNX14 is unknown. The yeast homolog, Mdm1, functions in endoplasmic reticulum (ER)-lysosome/vacuole inter-organelle tethering, but functional conservation in mammals is still required. Here, we show that loss of SNX14 alters but does not block autophagic flux. In addition, we find that SNX14 is an ER-associated protein that functions in neutral lipid homeostasis and inter-organelle crosstalk. SNX14 requires its N-terminal transmembrane helices for ER localization, while the Phox homology (PX) domain is dispensable for subcellular localization. Both SNX14-mutant fibroblasts and SNX14KO HEK293 cells accumulate aberrant cytoplasmic vacuoles, suggesting defects in endolysosomal homeostasis. However, ER-late endosome/lysosome contact sites are maintained in SNX14KO cells, indicating that it is not a prerequisite for ER-endolysosomal tethering. Further investigation of SNX14- deficiency indicates general defects in neutral lipid metabolism. SNX14KO cells display distinct perinuclear accumulation of filipin in LAMP1-positive lysosomal structures indicating cholesterol accumulation. Consistent with this, SNX14KO cells display a slight but detectable decrease in cholesterol ester levels, which is exacerbated with U18666A. Finally, SNX14 associates with ER-derived lipid droplets (LD) following oleate treatment, indicating a role in ER-LD crosstalk. We therefore identify an important role for SNX14 in neutral lipid homeostasis between the ER, lysosomes and LDs that may provide an early intervention target to alleviate the clinical symptoms of SCAR20.
Assuntos
Retículo Endoplasmático/genética , Metabolismo dos Lipídeos/genética , Nexinas de Classificação/genética , Ataxias Espinocerebelares/genética , Autofagia/genética , Retículo Endoplasmático/metabolismo , Endossomos , Técnicas de Inativação de Genes , Células HEK293 , Homeostase/efeitos dos fármacos , Humanos , Proteínas de Filamentos Intermediários/genética , Gotículas Lipídicas/metabolismo , Lisossomos/efeitos dos fármacos , Lisossomos/genética , Mutação , Ácido Oleico/farmacologia , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Nexinas de Classificação/deficiência , Nexinas de Classificação/metabolismo , Ataxias Espinocerebelares/metabolismo , Ataxias Espinocerebelares/fisiopatologiaRESUMO
Nonsyndromic cleft lip with/without cleft palate (nsCL/P) and nonsyndromic cleft palate only (nsCPO) are the most frequent subphenotypes of orofacial clefts. A common syndromic form of orofacial clefting is Van der Woude syndrome (VWS) where individuals have CL/P or CPO, often but not always associated with lower lip pits. Recently, â¼5% of VWS-affected individuals were identified with mutations in the grainy head-like 3 gene (GRHL3). To investigate GRHL3 in nonsyndromic clefting, we sequenced its coding region in 576 Europeans with nsCL/P and 96 with nsCPO. Most strikingly, nsCPO-affected individuals had a higher minor allele frequency for rs41268753 (0.099) than control subjects (0.049; p = 1.24 × 10(-2)). This association was replicated in nsCPO/control cohorts from Latvia, Yemen, and the UK (pcombined = 2.63 × 10(-5); ORallelic = 2.46 [95% CI 1.6-3.7]) and reached genome-wide significance in combination with imputed data from a GWAS in nsCPO triads (p = 2.73 × 10(-9)). Notably, rs41268753 is not associated with nsCL/P (p = 0.45). rs41268753 encodes the highly conserved p.Thr454Met (c.1361C>T) (GERP = 5.3), which prediction programs denote as deleterious, has a CADD score of 29.6, and increases protein binding capacity in silico. Sequencing also revealed four novel truncating GRHL3 mutations including two that were de novo in four families, where all nine individuals harboring mutations had nsCPO. This is important for genetic counseling: given that VWS is rare compared to nsCPO, our data suggest that dominant GRHL3 mutations are more likely to cause nonsyndromic than syndromic CPO. Thus, with rare dominant mutations and a common risk variant in the coding region, we have identified an important contribution for GRHL3 in nsCPO.
Assuntos
Fissura Palatina/genética , Proteínas de Ligação a DNA/genética , Predisposição Genética para Doença , Fases de Leitura Aberta , Fatores de Transcrição/genética , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/genética , Alelos , Estudos de Casos e Controles , Fenda Labial/diagnóstico , Fenda Labial/genética , Fissura Palatina/diagnóstico , Cistos/diagnóstico , Cistos/genética , Humanos , Lábio/anormalidades , Mutação , Polimorfismo de Nucleotídeo Único , Grupos Raciais/genéticaRESUMO
In this study, differences in the placental microbiota from term and preterm deliveries in a large pregnancy cohort in the United Kingdom were studied by using 16S-targeted amplicon sequencing. The impacts of contamination from DNA extraction, PCR reagents, and the delivery itself were also examined. A total of 400 placental samples from 256 singleton pregnancies were analyzed, and differences between spontaneous preterm-, nonspontaneous preterm-, and term-delivered placentas were investigated. DNA from recently delivered placentas was extracted, and screening for bacterial DNA was carried out by using targeted sequencing of the 16S rRNA gene on the Illumina MiSeq platform. Sequenced reads were analyzed for the presence of contaminating operational taxonomic units (OTUs) identified via sequencing of negative extraction and PCR-blank samples. Differential abundances and between-sample (beta) diversity metrics were then compared. A large proportion of the reads sequenced from the extracted placental samples mapped to OTUs that were also found for negative extractions. Striking differences in the compositions of samples were also observed, according to whether the placenta was delivered abdominally or vaginally, providing strong circumstantial evidence for delivery contamination as an important contributor to observed microbial profiles. When OTU- and genus-level abundances were compared between the groups of interest, a number of organisms were enriched in the spontaneous preterm-delivery cohort, including organisms that have been associated previously with adverse pregnancy outcomes, specifically Mycoplasma spp. and Ureaplasma spp. However, analyses of the overall community structure did not reveal convincing evidence for the existence of a reproducible "preterm placental microbiome."IMPORTANCE Preterm birth is associated with both psychological and physical disabilities and is the leading cause of infant morbidity and mortality worldwide. Infection is known to be an important cause of spontaneous preterm birth, and recent research has implicated variation in the "placental microbiome" in the risk of preterm birth. Consistent with data from previous studies, the abundances of certain clinically relevant species differed between spontaneous preterm- and nonspontaneous preterm- or term-delivered placentas. These results support the view that a proportion of spontaneous preterm births have an intrauterine-infection component. However, an additional observation from this study was that a substantial proportion of sequenced reads were contaminating reads rather than DNA from endogenous, clinically relevant species. This observation warrants caution in the interpretation of sequencing outputs from low-biomass samples such as the placenta.
Assuntos
Bactérias/classificação , Microbiota , Placenta/microbiologia , Nascimento Prematuro/microbiologia , Bactérias/genética , Bactérias/isolamento & purificação , Infecções Bacterianas/microbiologia , Estudos de Coortes , DNA Bacteriano/análise , Feminino , Humanos , Recém-Nascido , Microbiota/genética , Gravidez , RNA Ribossômico 16S/genética , Reino Unido , Vagina/microbiologiaRESUMO
Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a rare cause of pulmonary hypertension in newborns. Maternally inherited point mutations in Forkhead Box F1 gene (FOXF1), deletions of the gene, or its long-range enhancers on the maternal allele are responsible for this neonatal lethal disorder. Here, we describe monozygotic twins and one full-term newborn with ACD and gastrointestinal malformations caused by de novo mutations of FOXF1 on the maternal-inherited alleles. Since this parental transmission is consistent with genomic imprinting, the parent-of-origin specific monoallelic expression of genes, we have undertaken a detailed analysis of both allelic expression and DNA methylation. FOXF1 and its neighboring gene FENDRR were both biallelically expressed in a wide range of fetal tissues, including lung and intestine. Furthermore, detailed methylation screening within the 16q24.1 regions failed to identify regions of allelic methylation, suggesting that disrupted imprinting is not responsible for ACDMPV.
Assuntos
Fatores de Transcrição Forkhead/genética , Impressão Genômica , Síndrome da Persistência do Padrão de Circulação Fetal/genética , Alvéolos Pulmonares/anormalidades , Hibridização Genômica Comparativa , Metilação de DNA/genética , Feminino , Humanos , Hipertensão Pulmonar , Recém-Nascido , Herança Materna/genética , Mutação , Síndrome da Persistência do Padrão de Circulação Fetal/complicações , Síndrome da Persistência do Padrão de Circulação Fetal/patologia , Gravidez , Alvéolos Pulmonares/patologia , Gêmeos MonozigóticosRESUMO
Intellectual disability and cerebellar atrophy occur together in a large number of genetic conditions and are frequently associated with microcephaly and/or epilepsy. Here we report the identification of causal mutations in Sorting Nexin 14 (SNX14) found in seven affected individuals from three unrelated consanguineous families who presented with recessively inherited moderate-severe intellectual disability, cerebellar ataxia, early-onset cerebellar atrophy, sensorineural hearing loss, and the distinctive association of progressively coarsening facial features, relative macrocephaly, and the absence of seizures. We used homozygosity mapping and whole-exome sequencing to identify a homozygous nonsense mutation and an in-frame multiexon deletion in two families. A homozygous splice site mutation was identified by Sanger sequencing of SNX14 in a third family, selected purely by phenotypic similarity. This discovery confirms that these characteristic features represent a distinct and recognizable syndrome. SNX14 encodes a cellular protein containing Phox (PX) and regulator of G protein signaling (RGS) domains. Weighted gene coexpression network analysis predicts that SNX14 is highly coexpressed with genes involved in cellular protein metabolism and vesicle-mediated transport. All three mutations either directly affected the PX domain or diminished SNX14 levels, implicating a loss of normal cellular function. This manifested as increased cytoplasmic vacuolation as observed in cultured fibroblasts. Our findings indicate an essential role for SNX14 in neural development and function, particularly in development and maturation of the cerebellum.
Assuntos
Ataxia Cerebelar/genética , Deficiência Intelectual/genética , Nexinas de Classificação/genética , Sequência de Bases , Ataxia Cerebelar/patologia , Mapeamento Cromossômico , Códon sem Sentido/genética , Feminino , Fibroblastos/ultraestrutura , Redes Reguladoras de Genes/genética , Genes Recessivos/genética , Humanos , Deficiência Intelectual/patologia , Masculino , Microscopia Eletrônica , Dados de Sequência Molecular , Linhagem , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNARESUMO
Imprinted gene clusters are regulated by long noncoding RNAs (lncRNAs), CCCTC binding factor (CTCF)-mediated boundaries, and DNA methylation. DIRAS3 (also known as ARH1 or NOEY1) is an imprinted gene encoding a protein belonging to the RAS superfamily of GTPases and is located within an intron of a lncRNA called GNG12-AS1. In this study, we investigated whether GNG12-AS1 is imprinted and coregulated with DIRAS3. We report that GNG12-AS1 is coexpressed with DIRAS3 in several tissues and coordinately downregulated with DIRAS3 in breast cancers. GNG12-AS1 has several splice variants, all of which initiate from a single transcription start site. In placenta tissue and normal cell lines, GNG12-AS1 is biallelically expressed but some isoforms are allele-specifically spliced. Cohesin plays a role in allele-specific splicing of GNG12-AS1. In breast cancer cell lines with loss of DIRAS3 imprinting, DIRAS3 and GNG12-AS1 are silenced in cis and the remaining GNG12-AS1 transcripts are predominantly monoallelic. The GNG12-AS1 locus, which includes DIRAS3, provides an example of imprinted cotranscriptional splicing and a potential model system for studying the long-range effects of CTCF-cohesin binding on splicing and transcriptional interference.
Assuntos
Neoplasias da Mama/genética , Proteínas de Ciclo Celular/genética , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/genética , Impressão Genômica , RNA Longo não Codificante/genética , Proteínas rho de Ligação ao GTP/genética , Alelos , Processamento Alternativo , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Proteínas Cromossômicas não Histona/metabolismo , Metilação de DNA , Feminino , Regulação da Expressão Gênica , Humanos , Íntrons , Placenta/citologia , Placenta/metabolismo , Gravidez , RNA Longo não Codificante/metabolismo , Sítio de Iniciação de Transcrição , Transcrição Gênica , Proteínas rho de Ligação ao GTP/metabolismo , CoesinasRESUMO
Birth weight is an important indicator of both perinatal and adult health, but little is known about the genetic factors contributing to its variability. Intrauterine growth restriction is a leading cause of perinatal morbidity and mortality and is also associated with adult disease. A significant correlation has been reported between lower birth weight and increased expression of the maternal PHLDA2 allele in term placenta (the normal imprinting pattern was maintained). However, a mechanism that explains the transcriptional regulation of PHLDA2 on in utero growth has yet to be described. In this study, we sequenced the PHLDA2 promoter region in 263 fetal DNA samples to identify polymorphic variants. We used a luciferase reporter assay to identify in the PHLDA2 promoter a 15 bp repeat sequence (RS1) variant that significantly reduces PHLDA2-promoter efficiency. RS1 genotyping was then performed in three independent white European normal birth cohorts. Meta-analysis of all three (total n = 9,433) showed that maternal inheritance of RS1 resulted in a significant 93 g increase in birth weight (p = 0.01; 95% confidence interval [CI] = 22-163). Moreover, when the mother was homozygous for RS1, the influence on birth weight was 155 g (p = 0.04; 95% CI = 9-300), which is a similar magnitude to the reduction in birth weight caused by maternal smoking.
Assuntos
Peso ao Nascer/genética , Feto/metabolismo , Impressão Genômica , Proteínas Nucleares/genética , Regiões Promotoras Genéticas , Adulto , Sequência de Bases , Feminino , Variação Genética , Humanos , Recém-Nascido de Baixo Peso , Recém-Nascido , Masculino , Dados de Sequência Molecular , Sequências Repetitivas de Ácido Nucleico/genética , População Branca/genéticaRESUMO
Annexin A5 is a placental anti-coagulant protein that contains four nucleotide substitutions (M2 haplotype) in its promoter. This haplotype is a risk factor for recurrent spontaneous abortion (RSA). The influence of the M2 haplotype in the gestational timing of spontaneous abortions, paternal risk and relationships with known risk factors were investigated. European couples (n = 500) who had experienced three or more consecutive spontaneous abortions, and two fertile control groups, were selected for this study. The allele frequency of M2 was significantly higher among patients who had experienced early RSA than among controls (P = 0.002). No difference was found between controls and patients who had undergone late spontaneous abortions. No difference was found between patients who had experienced RSA who had a live birth or no live births, or between patients who were positive or negative for known risk factors. Male and female partners in each group had similar allele frequencies of M2. The M2 haplotype is a risk factor for early spontaneous abortions, before the 12th week of gestation, and confers about the same relative risk to carriers of both sexes. Having one or more M2 allele(s) in combination with other risk factors further increases the RSA risk.
Assuntos
Aborto Habitual/genética , Anexina A5/genética , Haplótipos , Regiões Promotoras Genéticas , Adulto , Alelos , Feminino , Frequência do Gene , Predisposição Genética para Doença , Humanos , Masculino , Gravidez , Fatores de Risco , População Branca/genéticaRESUMO
Paternal duplications of chromosome 6q24, a region that contains the imprinted PLAGL1 and HYMAI transcripts, are associated with transient neonatal diabetes mellitus. A common feature of imprinted genes is that they tend to cluster together, presumably as a result of sharing common cis-acting regulatory elements. To determine the extent of this imprinted cluster in human and mouse, we have undertaken a systematic analysis of allelic expression and DNA methylation of the genes mapping within an â¼1.4-Mb region flanking PLAGL1/Plagl1. We confirm that all nine neighbouring genes are biallelically expressed in both species. In human we identify two novel paternally expressed PLAGL1 coding transcripts that originate from unique promoter regions. Chromatin immunoprecipitation for CTCF and the cohesin subunits RAD21 and SMC3 reveals evolutionarily conserved binding sites within unmethylated regions â¼5 kb downstream of the PLAGL1 differentially methylated region and within the PLAGL1 3' untranslated region (UTR). Higher-order chromatin looping occurs between these regions in both expressing and non-expressing tissues, forming a non-allelic chromatin loop around the PLAGL1/Plagl1 gene. In placenta and brain tissues, we identify an additional interaction between the PLAGL1 P3/P4 promoters and the unmethylated element downstream of the PLAGL1 differentially methylated region that we propose facilitates imprinted expression of these alternative isoforms.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Cromatina/química , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Ligação a DNA/genética , Impressão Genômica , Proteínas Repressoras/metabolismo , Alelos , Animais , Fator de Ligação a CCCTC , Proteínas de Ciclo Celular/genética , Cromatina/metabolismo , Cromossomos Humanos Par 6 , Proteínas de Ligação a DNA/metabolismo , Feminino , Genes Supressores de Tumor , Genótipo , Humanos , Camundongos , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Placenta/metabolismo , Gravidez , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , RNA Mensageiro/genética , Fatores de Transcrição/genética , CoesinasRESUMO
We report on two Portuguese sisters with a very similar phenotype characterized by severe intellectual disability, absent speech, relative macrocephaly, coarse face, cerebellar hypotrophy, and severe ataxia. Additional common features include increased thickness of the cranial vault, delayed dental eruption, talipes equino-varus, clinodactyly, and camptodactyly of the fifth finger. The older sister has retinal dystrophy and the younger sister has short stature. Their parents are consanguineous. We suggest this condition constitutes a previously unreported autosomal recessive entity.
Assuntos
Cerebelo/anormalidades , Ossos Faciais/anormalidades , Deficiência Intelectual/diagnóstico , Megalencefalia/diagnóstico , Malformações do Sistema Nervoso/diagnóstico , Irmãos , Anormalidades Múltiplas , Encéfalo/patologia , Criança , Consanguinidade , Deficiências do Desenvolvimento/diagnóstico , Fácies , Feminino , Deformidades Congênitas da Mão/diagnóstico por imagem , Deformidades Congênitas da Mão/patologia , Humanos , Imageamento por Ressonância Magnética , Linhagem , Fenótipo , Radiografia , Crânio/diagnóstico por imagem , Crânio/patologia , Síndrome , Adulto JovemRESUMO
The relationship between the parental genomes in terms of the future growth and development of their offspring is not critical. For the majority of the genome the tissue-specific gene expression and epigenetic status is shared between the parents equally, with both alleles contributing without parental bias. For a very small number of genes the rules change and control of expression is restricted to a specific, parentally derived allele, a phenomenon known as genomic imprinting. The insulin-like growth factor 2 (Igf2/IGF2) is a robustly imprinted gene, important for fetal growth in both mice and humans. In utero IGF2 exhibits paternal expression, which is controlled by several mechanisms, including the maternally expressing untranslated H19 gene. In the study by Soubry et al., a correlation is drawn between the IGF2 methylation status in fetal cord blood leucocytes, and the obesity status of the father from whom the active IGF2 allele is derived through his sperm. These data imply that paternal obesity affects the normal IGF2 methylation in the sperm and this in turn alters the expression of IGF2 in the baby.
Assuntos
Metilação de DNA , Epigênese Genética , Pai , Fator de Crescimento Insulin-Like II/genética , Obesidade/complicações , Lesões Pré-Concepcionais , Animais , Feminino , Humanos , Masculino , GravidezRESUMO
Here we report on a Portuguese family with three sisters who shared moderate intellectual disability, unusual facial morphology (short palpebral fissures; broad nasal tip; thin upper and lower vermillion; broad and pointed chin) and hand anomalies in two of them (short left third and fifth right metacarpals in one case; marked syndactyly between the third and fourth fingers in another). One of the sisters had microcephaly and short stature, and the other two were obese. Obesity and somewhat similar facial features were also present in the otherwise healthy mother. Despite the overlap with several known syndromes (Albright osteodystrophy; Filippi syndrome; Rubinstein-Taybi syndrome; microdeletion 2q37), we suggest this condition is previously unreported, and most likely displays an autosomal recessive pattern of inheritance. © 2013 Wiley Periodicals, Inc.
Assuntos
Anormalidades Múltiplas/diagnóstico , Deformidades Congênitas da Mão/diagnóstico , Deficiência Intelectual/diagnóstico , Anormalidades Múltiplas/genética , Adulto , Idoso , Criança , Aberrações Cromossômicas , Fácies , Feminino , Genótipo , Deformidades Congênitas da Mão/genética , Humanos , Deficiência Intelectual/genética , Masculino , Pessoa de Meia-Idade , Irmãos , Síndrome , Inativação do Cromossomo XRESUMO
Induced pluripotent stem cells (iPSCs) with potential for therapeutic applications can be derived from somatic cells via ectopic expression of a set of limited and defined transcription factors. However, due to risks of random integration of the reprogramming transgenes into the host genome, the low efficiency of the process, and the potential risk of virally induced tumorigenicity, alternative methods have been developed to generate pluripotent cells using nonintegrating systems, albeit with limited success. Here, we show that c-KIT+ human first-trimester amniotic fluid stem cells (AFSCs) can be fully reprogrammed to pluripotency without ectopic factors, by culture on Matrigel in human embryonic stem cell (hESC) medium supplemented with the histone deacetylase inhibitor (HDACi) valproic acid (VPA). The cells share 82% transcriptome identity with hESCs and are capable of forming embryoid bodies (EBs) in vitro and teratomas in vivo. After long-term expansion, they maintain genetic stability, protein level expression of key pluripotency factors, high cell-division kinetics, telomerase activity, repression of X-inactivation, and capacity to differentiate into lineages of the three germ layers, such as definitive endoderm, hepatocytes, bone, fat, cartilage, neurons, and oligodendrocytes. We conclude that AFSC can be utilized for cell banking of patient-specific pluripotent cells for potential applications in allogeneic cellular replacement therapies, pharmaceutical screening, and disease modeling.
Assuntos
Líquido Amniótico/efeitos dos fármacos , Inibidores de Histona Desacetilases/farmacologia , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Ácido Valproico/farmacologia , Líquido Amniótico/citologia , Diferenciação Celular , Linhagem Celular , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Genoma Humano , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Cariotipagem , Cinética , Fator 4 Semelhante a Kruppel , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , Masculino , Proteína Homeobox Nanog , Fator 3 de Transcrição de Octâmero/genética , Fator 3 de Transcrição de Octâmero/metabolismo , Fenótipo , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismo , Análise de Sequência de DNA , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcriptoma , Transgenes , Inativação do Cromossomo X/efeitos dos fármacosRESUMO
Imprinted retrotransposed genes share a common genomic organization including a promoter-associated differentially methylated region (DMR) and a position within the intron of a multi-exonic 'host' gene. In the mouse, at least one transcript of the host gene is also subject to genomic imprinting. Human retrogene orthologues are imprinted and we reveal that human host genes are not imprinted. This coincides with genomic rearrangements that occurred during primate evolution, which increase the separation between the retrogene DMRs and the host genes. To address the mechanisms governing imprinted retrogene expression, histone modifications were assayed at the DMRs. For the mouse retrogenes, the active mark H3K4me2 was associated with the unmethylated paternal allele, while the methylated maternal allele was enriched in repressive marks including H3K9me3 and H4K20me3. Two human retrogenes showed monoallelic enrichment of active, but not of repressive marks suggesting a partial uncoupling of the relationship between DNA methylation and repressive histone methylation, possibly due to the smaller size and lower CpG density of these DMRs. Finally, we show that the genes immediately flanking the host genes in mouse and human are biallelically expressed in a range of tissues, suggesting that these loci are distinct from large imprinted clusters.
Assuntos
Impressão Genômica , Histonas/metabolismo , Retroelementos , Alelos , Animais , Cromatina/metabolismo , Metilação de DNA , Humanos , Camundongos , Regiões Promotoras GenéticasRESUMO
As a field of study, genomic imprinting has grown rapidly in the last 20 years, with a growing figure of around 100 imprinted genes known in the mouse and approximately 50 in the human. The imprinted expression of genes may be transient and highly tissue-specific, and there are potentially hundreds of other, as yet undiscovered, imprinted transcripts. The placenta is notable amongst mammalian organs for its high and prolific expression of imprinted genes. This review discusses the development of the human placenta and focuses on the function of imprinting in this organ. Imprinting is potentially a mechanism to balance parental resource allocation and it plays an important role in growth. The placenta, as the interface between mother and fetus, is central to prenatal growth control. The expression of genes subject to parental allelic expression bias has, over the years, been shown to be essential for the normal development and physiology of the placenta. In this review we also discuss the significance of genes that lack conservation of imprinting between mice and humans, genes whose imprinted expression is often placental-specific. Finally, we illustrate the importance of imprinting in the postnatal human in terms of several human imprinting disorders, with consideration of the brain as a key organ for imprinted gene expression after birth.